1. Field of the Invention
The present invention relates to a module IC handler used for automatically handling the module ICs throughout test processes for the module ICs, and more particularly to a method and apparatus for circulating pallets in an elevator unit of the module IC handler and which sequentially transfers pallets containing test or customer trays to a loading position or an unloading position.
2. Description of the Conventional Art
Typically, a module IC 1 refers to, as shown in FIG. 1, a structure provided with a substrate whose one side or both sides thereof is used for for fixedly mounting a plurality of ICs and electric components, for example, by soldering, and has a function for extending a capacity when it is coupled to a mother substrate.
Such a module IC provides higher added-value when sold, as compared with individual sale of each IC as a final product. To this end, the IC manufactures tend to develop it as a main product and sell it.
However, the module IC as a product available from the market is relatively expensive and thus entails higher reliability as an important factor therefor. This requires strict quality test for passing only product determined to be good, and otherwise, discarding all the module ICs determined to be not good.
In the prior art, there has been no apparatus for automatically loading the module ICs as final products into a test socket, testing the same, classifying into respective categories depending upon the test results and then unloading the classified modules into the customer trays (not shown).
To test the final product of module IC, the operator manually has to pick up one piece of the module IC from the test tray in which the module ICs are contained therein, load it into a test socket, conducts the tests for a time period preset, and finally classify the module IC depending upon the test result in order to put it the customer tray. This results in lower productivity due to manual work.
Further, such tedious repeated manual work contributes to lower productivity.
Inside of the test trays and the customer trays, respectively, is provided with a plurality of insertion slots for vertically putting therein the module IC 1.
To solve such a problem, the inventors developed an automatic module IC handler adapted to test the module ICs, which was disclosed in Korean patent and utility model applications (available from Mirae Co. xe2x80x9cMR 7100, MR 7200xe2x80x9d).
FIGS. 2 to 4 show a disclosure of Korean utility model application serial No 96-8320, 1996.
FIG. 2 is a front view showing the prior apparatus, FIG. 3 is a side view with some portions the FIG. 2 apparatus omitted, and FIG. 4 is a plan view of the apparatus shown in FIG. 2.
There is shown an upward and downward movable elevator 4 coupled to a guide rod 3 fixed at a support plate 2, and having therein pallets a4 operable like a drawer.
The pallet positioned at a loading side among the pallets 5 is used to carry thereon the test tray 6 containing the module ICs to be tested, whereas the pallet positioned at an unloading side used to carry thereon the customer trays 7 containing the test-finished module Ics.
Between the support rods 3 is disposed a lead screw 9 rotated by a drive of the motor 8 and into which a guide block 10 fixed at both sides of the elevator 4 is screwed.
A retractable slider 13, which is moved along a guide rail 12, is disposed over an installation plate 11 disposed in the loading side and unloading sides, respectively. Further, the slider 13 is provide with a pair of fingers 15 being able to be widen or narrowed by an action of the cylinder 14. Also, the pallet 5 has one surface oppositely facing the slider 13 and at which a suspension protrusion 5a is formed.
The apparatus thus constructed begins to operate when the test trays 6 fully filled with the module ICs to be tested are, respectively, placed on the pallets 6 in the loading side elevator, and also when empty customer trays 7 to be filled with the test-completed module ICs are placed on the pallets 5 in the unloading side elevator.
With the pair of fingers 15 opened by an OFF state of the cylinder 14 installed in the slider 13, an activated motor 8 elevates the elevator 4. If any one of pallets accommodated in the elevator reaches a horizontal plane of the slider 13, the slider 14 moves toward the pallet 5 as seen left in FIG. 4, at this time, the cylinder 14 activated shrinks the fingers 16 to hold the pallet 5 the slider 13.
Under such circumstances, returning to an initial state of the slider 13, the slider 13 is drawn to the loading or unloading position as seen right in FIG. 4. Therefore, the loading side picking-up means 16 sequentially picks up the modules ICs contained in the test tray 6 to then load it into the test socket or in carrier.
On the other hand, after all of module ICs in the test tray 6 being picke-up, the slider 13 pushes the pallet toward its associated elevator 4. With the holding state being released, the lead screw 9 into which a guide block 10 fixed at both sides of the elevator 4 is screwed is rotated by the motor to elevate the elevator 4 by one step.
The second pallet below the top pallet being thus held by the fingers 15 disposed in the slider 13 is drawn out. Therefore, it becomes possible to repeat the procedures as mentioned above.
However, although the prior apparatus as discussed above has an advantage in that the test or customer trays 5 or 6 may be stocked in the pallet 5 in the elevator 4 thus allowing automatic loading or unloading of the module ICs, the apparatus has the following drawbacks.
Firstly, to pull out the pallet 5 in the elevator, it requires that the elevator 4 be each time elevated by one step above the installation plate 11, which results in an increase in height of the apparatus.
Secondly, to load the module ICs or to unload the test-completed ICs into the customer tray, it requires that the slider 13 is moved to hold the pallet 5 in the elevator 4 by the fingers 15 and the pallet held is then to be moved to the loading position. Thus, a total area occupied by the apparatus becomes wider, which results in an increase in the installation area.
Finally, after all of the module ICs in the test tray 6 having been placed on each pallet 5 are loaded, or all of the test-finished module ICs in the customer tray 7 are unloaded, the operator lowers the elevator 4 up to the bottom dead point, pulls the tray from the pallet and then puts individual new test or customer trays into each pallet 5 one by one. Thus, a stand-by interval is required during which the elevator returns, thus resulting in lower availability of the high-cost apparatus.
Therefore, it is an object of the present invention to enable loading and unloading operations for module ICs, without further elevating pallet over an installation plate, and to provide sequential transferring operations for the pallet on which test or customer tray is placed.
It is another object of the present invention to minimize a stand-by interval introduced by the loading and unloading operations for the test and customer trays.
Theses objects are accomplished by the present invention provding, for a module IC handler including an elevator unit, a method for circulating pallets in the elevator unit comprising the steps of: transferring a transfer having holding means to a position over a pallet positioned at a loading or unloading position and, simultaneously, upwardly moving a downer positioned at a bottom dead point to a top dead point; downwardly moving the holding means to hold the pallet and thereafter upwardly moving the holding means carrying the pallet; moving downward the holding means after the transfer is transferred to a rotation position, placing the pallet on the top surface a downer, and returning to an initial state of the holding means; releasing locking means to which the pallets at the loading or unloading position are locked, subsequently opening a stopper for preventing the pallets being dropped when simultaneous upward movement of the plural pallets placed on a loading or unloading elevation plate are made, and exposing to the loading or unloading position the top pallet; the locking means locking the top pallet exposed; returning to an initial state of said stopper opened, and moving downward to the bottom dead point the elevation plate with the bottom plate which is suspended by the stopper; aligning the top level of the pallet placed on the descending downer with the top level of the loading side or unloading side elevation plate; and transferring the pallet placed on the downer to the top surface of the loading side or unloading side elevation plate.
Also, according to another aspect of the present invention accomplishing the above objects, there is provided for a module IC handler including an elevator unit, an apparatus for circulating pallets in the elevator unit comprising: loading side and unloading elevation units each having an upward and downward movable elevation plate installed between parallel side plates; first driving means for upwardly moving each elevation plate; a plurality of pallets each having a top surface on which a test tray or a customer tray is placed, and which are vertically deposited on each elevation plate; stopper means installed oppositely to each side plate, for controlling the descending action of the pallet; locking means installed, respectively, at loading and unloading positions both of which are in an upper side of the side plate, for locking the top pallet being exposed to the loading or unloading position; a rotation position between the elevator units in respective loading and unloading sides, for downwardly moving the pallet; a transfer for holding the pallet at the loading or unloading position and transferring same to the rotation position; an upward and downward movable downer installed at the rotation position, for transferring the pallet moved by the transfer to the bottom dead point; second driving means for upwardly moving the downer; and distributing means disposed at the bottom dead point of the rotation position, for transferring the pallet moved down by the downer to the elevator unit of the loading or unloading side.